Response of anestrous ewes to the ram effect after follicular wave synchronization with a single dose of estradiol-17?

Abstract

-Anestrous ewes respond to the introduction of rams with either an ovulation within 2-3 days that may be followed by luteal phases of normal or short length, with delayed ovulations (5-6 days later), or with the luteinization of follicles. The aim of this work was to study the relationship between the growth status of the largest follicle present when rams are introduced and the type of ovarian response in non-treated ewes and in ewes treated with estradiol-17β before ram introduction. Thirteen anestrous Corriedale ewes were divided into 2 groups: E2 (n = 7) and C (n = 6). The E2 ewes received a single dose of 50 µg estradiol-17β 5 days before the introduction of the rams to synchronize the onset of their follicle waves, while C ewes remained untreated. When the rams were introduced, all E2 ewes had the largest follicle in a growing stage in contrast with the C ewes (3 out of 6; P < 0.05). Five C and 4 E2 ewes ovulated after the introduction of the rams (Day 3.4 ± 0.4 for C vs. 4.8 ± 0.3 for E2 ewes, respectively, P < 0.05). Only one ewe from each group developed a normal luteal phase; 4 C and 3 E2 ewes had short luteal phases. One C ewe and 2 E2 ewes had short luteal phases originating from follicles that did not ovulate. After the first luteal phase, all ewes returned to anestrus without a second ovulation or luteal phase. The remaining E2 ewe did not ovulate or show any changes in progesterone serum concentrations. We conclude that the growth status of the largest follicle alone does not determine the ovarian responding pattern of anestrous ewes to the ram effect. follicular dynamics / ultrasound / ram stimulus / ovulation / non-breeding season

Influence of Male to Female Ratio on Hormone Profiles and Reproductive Performance of Anestrus Postpartum Ewes Subjected to the Male Effect

“…Conception rate on first service was higher than that of the second service on MFR20 and MFR30 groups where the interaction between genders was higher. This finding demystifies the observation that the first estrus due to the male effect could be anovulatory [32] or, if ovulation occurs, corpum luteum is weak, lapses rapidly and leads to occurrence of short estrus cycles [6]. Moreover, it shows that male to female ratios of 1:30 or higher, even under controlled mating, should be reanalyzed and considered for adoption even if total conception rates did not differ between groups.…”

Eicosapentaenoic acid down-regulates expression of the selenoprotein P gene by inhibiting SREBP-1c protein independently of the AMP-activated protein kinase pathway in H4IIEC3 hepatocytes

“…To our knowledge, this is the first study to show that a polyunsaturated fatty acid EPA down-regulates diabetes-associated hepatokine SELENOP expression by inactivating SREBP-1c in H4IIEC3 hepatocytes. Several lines of evidence have suggested that -3 PUFAs, such as EPA and docosahexaenoic acid (DHA) protect against high-fat diet-induced insulin resistance (38). Neschen et al (24) demonstrated that EPA protects mice from high-fat diet-induced hepatic insulin resistance by binding directly to peroxisome proliferator-activated receptor ␣ and thus decreasing diacylglycerol levels in the liver of mice.…”

New approaches to superovulation and embryo transfer in small ruminants

“…However, progesterone alone is not effective in synchronising the emergence of a new wave at a predictable time. Conversely, 17β-oestradiol alone induces an initial suppression of serum FSH concentrations, followed by an FSH surge 2-3 days later (Meikle et al 2001;Ungerfeld et al 2004). Recently, a treatment combining medroxiprogesterone and 17β-oestradiol resulted in an FSH surge and emergence of a new wave approximately 3-5 days after oestradiol treatment .…”